I have a similar problem, but it's not dependent on video files or camera or card type. Mine seems to be somthing with the usb controller. When I copy the raw files from the camera to an external hard drive, I'll end up with sporadic raw files being corrupt-similar in look to the one shown here, but some image is visible. If I copy them to the internal hard drive, I don't have a problem. I haven't been able to fix it, but just work around it by initially copying all raw files to the internal hd and then copying them to the external hd. I have a 6100xps Dell and dell says it's not they're issue which I'm 95% sure it is a hardware problem. Did you find out it is a ram problem for you?